U.S. patent number 6,916,998 [Application Number 10/311,474] was granted by the patent office on 2005-07-12 for weight measuring device and person weight measuring equipment including the weight measuring device.
This patent grant is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Shusaku Kawasaki, Kiyoshi Saito, Tsuyoshi Tanaka, Shigehiro Yoshiuchi.
United States Patent |
6,916,998 |
Saito , et al. |
July 12, 2005 |
Weight measuring device and person weight measuring equipment
including the weight measuring device
Abstract
A weight measuring device comprising a base fixed to an object,
a strain detection substrate fixed to the base, a fitting pin fixed
to the strain detection substrate, an arm rotatably attached to the
base by a support pin, and a leaf spring with one end fixed to the
arm and the other end supported by the fitting pin. The weight
measuring device further comprises a second arm with one end
receiving the load of the object to be measured and the other end
fixed to the arm through a link pin. By the configuration of the
present invention, the load applied to the strain detection
substrate is reduced, and a weight measuring device improved in
detecting resolution is obtained. Furthermore, the weight measuring
device of the present invention is unitized, and the weight
measuring device can be easily built into various equipment.
Inventors: |
Saito; Kiyoshi (Osaka,
JP), Kawasaki; Shusaku (Osaka, JP),
Yoshiuchi; Shigehiro (Osaka, JP), Tanaka;
Tsuyoshi (Osaka, JP) |
Assignee: |
Matsushita Electric Industrial Co.,
Ltd. (Osaka, JP)
|
Family
ID: |
27346537 |
Appl.
No.: |
10/311,474 |
Filed: |
June 23, 2003 |
PCT
Filed: |
April 15, 2002 |
PCT No.: |
PCT/JP02/03720 |
371(c)(1),(2),(4) Date: |
June 23, 2003 |
PCT
Pub. No.: |
WO02/08423 |
PCT
Pub. Date: |
October 24, 2002 |
Foreign Application Priority Data
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Apr 16, 2001 [JP] |
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2001-116599 |
Feb 14, 2002 [JP] |
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2002-036497 |
Feb 18, 2002 [JP] |
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2002-039504 |
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Current U.S.
Class: |
177/144; 180/273;
280/735 |
Current CPC
Class: |
B60N
2/002 (20130101); G01G 19/4142 (20130101); B60R
21/01516 (20141001) |
Current International
Class: |
B60N
2/00 (20060101); G01G 19/414 (20060101); G01G
19/40 (20060101); B60R 21/01 (20060101); B60R
021/32 (); G01G 019/52 (); B60K 028/04 () |
Field of
Search: |
;177/136,144,210R
;180/273 ;280/735 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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11-001153 |
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Jan 1999 |
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JP |
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2000-258232 |
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Sep 2000 |
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JP |
|
Primary Examiner: Gibson; Randy W.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack,
L.L.P.
Claims
What is claimed is:
1. A weight measuring device comprising: a base arranged to be
fixed to an object to be mounted; a strain detection substrate
attached to said base; a fitting pin fixed to said strain detection
substrate; a first arm rotatably attached to said base by a support
pin; a leaf spring having one end fixed to said first arm and
another end supported by said fitting pin; a link pin supported by
a guide hole, said link pin being movable in a direction
perpendicular to a bottom of said base, said guide hole formed in
said base, and being supported by a slide hole to be movable in a
direction parallel to the bottom of said base, said slide hole
formed in said first arm; and a second arm having one end for
receiving a load of an object to be measured, and another end fixed
to said first arm by said link pin.
2. The weight measuring device of claim 1, wherein a part of said
first arm or said second arm comes into contact with the base when
a load exceeds a maximum measuring load of said weight measuring
device.
3. The weight measuring device of claim 1, wherein said leaf spring
is provided with a predetermined clearance from said fitting pin at
a portion supported by said fitting pin.
4. The weight measuring device of claim 1, wherein an inner wall of
said fitting pin at a portion for supporting said leaf spring has
one of an arcuate shape and a semicircular shape.
5. A weight measuring device comprising: a base arranged to be
fixed to an object to be mounted, said base having a slot formed
therein; a strain detection substrate attached to said base; a
fitting pin fixed to said strain detection substrate; a fixing pin
fixed to said base; a leaf spring supported by said fitting pin and
said fixing pin at both ends thereof; and an arm connected nearly
to a middle portion of said leaf spring, said arm being movable in
an up-and-down direction by receiving a weight of an object to be
measured; wherein a shaft which supports said leaf spring is
movable in an up-and-down direction in said slot formed in said
base.
6. The weight measuring device of claim 5, wherein said leaf spring
is provided with a predetermined clearance from said fixing pin at
a portion supported by said fixing pin.
7. The weight measuring device of claim 5, wherein said shaft comes
into contact with an inner wall of said slot when a load exceeds a
maximum measuring load of said weight measuring device.
8. A weight measuring device comprising: a base arranged to be
fixed to an object to be mounted; a strain detection substrate
attached to said base; a fitting pin fixed to said strain detection
substrate; and a leaf spring having a fork-shaped first end
comprising three beams, and a second end of said leaf spring
comprising a load applied portion for receiving a load, wherein
said fitting pin has an insert portion for holding a middle beam of
said three beams, and wherein outer beams at both sides of said
three beams have ends fixed to said base, respectively.
9. The weight measuring device of claim 8, wherein the middle beam
of said leaf spring held by said fitting pin is one of straight and
divided in shape.
10. The weight measuring device of claim 8, wherein said middle
beam is narrower in width than the beams at both sides.
11. The weight measuring device of claim 8, wherein an inner wall
of a portion for supporting said middle beam of said fitting pin is
one of arcuate and semicircular in shape.
12. The weight measuring device of claim 8, wherein the load
applied portion side of said leaf spring is divided into three
portions, both of side portions and a middle portion of said three
portions divided being bent opposite to each other and held by a
link pin, and said link pin supports an arm provided with a fixing
hole for the load applied portion.
13. The weight measuring device of claim 8, wherein a semicircular
projection is disposed at the load applied portion side of said
leaf spring, and said arm is arranged so as to hold said
semicircular projection.
14. The weight measuring device of claim 8, wherein a stopper for
controlling an amount of deformation of said leaf spring is
provided.
15. The weight measuring device of claim 1, wherein said base is
fixed to the chassis side of a vehicle, and one of said first arm
and said second arm is connected to a seat truck bottom of a
vehicle seat.
16. The weight measuring device of claim 1, wherein said base is
fixed to a seat truck of a vehicle seat, and one of said first arm
and said second arm is connected to the vehicle seat.
17. Person weight measuring equipment comprising the weight
measuring device of claim 1, said base of said weight measuring
device being fixed to a chassis side, and one of said first arm and
said second arm of said weight measuring device being fixed to a
seat truck bottom of a vehicle seat, wherein a seat weight and
person weight are measured by a load detected by said weight
measuring device.
18. Person weight measuring equipment comprising the weight
measuring device of claim 1, said base of said weight measuring
device being fixed to a seat truck of a vehicle seat, and one of
said first arm and said second arm of said weight measuring device
being fixed to said vehicle seat, wherein a seat weight and person
weight are measured by a load detected by said weight measuring
device.
19. The person weight measuring equipment of claim 18, wherein said
weight measuring equipment is installed at four corners of said
vehicle seat.
20. The weight measuring device of claim 5, wherein said base is
fixed to the chassis side of a vehicle, and said arm is connected
to a seat truck bottom of a vehicle seat.
21. The weight measuring device of claim 8, wherein said base is
fixed to the chassis side of a vehicle, and one of said leaf spring
and an arm connected to said leaf spring is connected to a seat
truck bottom of a vehicle seat.
22. The weight measuring device of claim 5, wherein said base is
fixed to a seat truck of a vehicle seat, and said arm is connected
to the vehicle seat.
23. The weight measuring device of claim 8, wherein said base is
fixed to a seat truck of a vehicle seat, and one of said leaf
spring and an arm connected to said leaf spring is connected to the
vehicle seat.
24. Person weight measuring equipment comprising the weight
measuring device of claim 5, the base of said weight measuring
device being fixed to a chassis side, and said arm of said weight
measuring device being fixed to a seat truck bottom of a vehicle
seat, wherein a seat weight and person weight are measured by a
load detected by said weight measuring device.
25. Person weight measuring equipment comprising the weight
measuring equipment of claim 8, the base of said weight measuring
device being fixed to a chassis side, and one of said leaf spring
and an arm connected to said leaf spring being fixed to a seat
truck bottom of a vehicle seat, wherein a seat weight and person
weight are measured by a load detected by said weight measuring
device.
26. Person weight measuring equipment comprising the weight
measuring device of claim 5, the base of said weight measuring
device being fixed to a seat truck of a vehicle seat, and said arm
of said weight measuring device being fixed to said vehicle seat,
wherein a seat weight and person weight are measured by a load
detected by said weight measuring device.
27. Person weight measuring equipment comprising the weight
measuring device of claim 8, the base of said weight measuring
device being fixed to a seat truck of a vehicle seat, and one of
said leaf spring and an arm connected to said leaf spring being
fixed to said vehicle seat, wherein a seat weight and person weight
are measured by a load detected by said weight measuring
device.
28. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 8, wherein said weight
measuring devices are installed at four corners of a vehicle seat,
respectively; for each of said weight measuring devices, one of
said leaf spring and an arm connected to said leaf spring is fixed
to a seat truck bottom of said vehicle seat, and said base is fixed
to a chassis side; and seat weight and person weight are measured
by a load detected by said weight measuring devices.
29. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 8, wherein said weight
measuring devices are installed at four corners of a vehicle seat,
respectively; for each of said weight measuring devices, one of
said leaf spring and an arm connected to said leaf spring is fixed
to said vehicle seat, and said base is fixed to a seat truck of a
vehicle seat; and seat weight and person weight are measured by a
load detected by said weight measuring devices.
30. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 5, wherein said weight
measuring devices are installed at four comers of a vehicle scat,
respectively; for each of said weight measuring devices, said arm
is fixed to a seat truck bottom of said vehicle seat, and said base
is fixed to a chassis side; and seat weight and person weight are
measured by a load detected by said weight measuring devices.
31. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 5, wherein said weight
measuring devices are installed at four comers of a vehicle seat,
respectively; for each of said weight measuring devices, said arm
is fixed to said vehicle seat, and said base is fixed to a seat
truck of a vehicle seat; and seat weight and person weight are
measured by a load detected by said weight measuring devices.
32. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 1, wherein said weight
measuring devices are installed at four corners of a vehicle seat,
respectively; for each of said weight measuring devices, one of
said first arm and said second arm is fixed to a seat truck bottom
of said vehicle seat, and said base is fixed to a chassis side; and
seat weight and person weight are measured by a load detected by
said weight measuring devices.
33. Person weight measuring equipment comprising four weight
measuring devices, each according to claim 1, wherein said weight
measuring devices are installed at four corners of a vehicle seat,
respectively; for each of said weight measuring devices, one of
said first arm and said second arm is fixed to said vehicle seat,
and said base is fixed to a seat truck of a vehicle seat; and seat
weight and person weight are measured by a load detected by said
weight measuring devices.
Description
TECHNICAL FIELD
The present invention relates to a weight measuring device for
measuring weights of objects, and driver and passenger (hereinafter
referred to as "person") weight measuring equipment for vehicles
using the same.
BACKGROUND ART
Recently, there has been a trend toward controlling the operation
of safety equipment according to the weight and constitution of a
person's body in order to improve the performance of seat belts and
air bags. For example, the vehicle judges whether the person
getting therein is a child or an adult, and adjusts an expanding
gas quantity and an expanding speed or stops the operation of the
air bag. Therefore, it is necessary to know the weight of the
person sitting on the seat by using some means. As an example of
such means, a system is proposed in that a strain sensor (load
cell) is disposed at four corners of seat rails in order to measure
the weight of the person by adding the loads vertically applied to
the load cell (Japanese Patent Laid-open Publication H11-1153).
As for a strain sensor for the person weight measuring equipment,
there is a demand for a small-sized sensor whose maximum measuring
load is about 50 kg. As such strain sensors, there are those having
a strain gauge stuck (or formed) on a sensor plate which is
deformed by the load, those based on a piezoelectric system, and
those using a static capacity sensor for detecting the displacement
of an elastic member which is deformed by the load.
In a case of such a weight measuring device and person weight
measuring equipment using same, the load of the object to be
measured is directly applied to the strain detectors disposed in
the equipment. Therefore, there arises a problem of a reduction in
detecting resolution if priority is given to an assurance of
strength of the detectors.
The present invention is intended to address such problem, and the
object of the invention is to provide a weight measuring device and
a person weight measuring equipment using the same. The weight
measuring device can improve the detecting resolution by reducing
the load applied to the strain detector as much as possible.
DISCLOSURE OF THE INVENTION
The weight measuring device of the present invention comprises a
base fixed to an object, a strain detection substrate attached to
the base, a fitting pin attached to the strain detection substrate,
an arm rotatably attached to the base by a support pin, and a leaf
spring with one end attached to the arm and the other end supported
by the fitting pin. Also, the weight measuring device of the
present invention further comprises a second arm with one end
receiving the load of the object to be measured and the other end
connected to the arm by a link pin. By the configuration of the
present invention, a weight measuring device has a reduced load
applied to the strain detection substrate and has an improved
detecting resolution. Also, the measuring device of the present
invention is unitized and can be easily built in various types of
equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a first preferred
embodiment of the present invention.
FIG. 2 is a side sectional view of the first preferred embodiment
of the present invention.
FIG. 3 is a plan view of the first preferred embodiment of the
present invention.
FIG. 4 is an exploded view of a second preferred embodiment of the
present invention.
FIG. 5 is a side sectional view of the second preferred embodiment
of the present invention.
FIG. 6 is a plan view of the second preferred embodiment of the
present invention.
FIG. 7 is a partly detailed view for describing the operation of an
arm.
FIG. 8A is a front view of a fitting pin showing a modified
configuration of the second preferred embodiment of the present
invention.
FIG. 8B is a side view of the modified configuration of the second
preferred embodiment of the present invention.
FIG. 8C is a partly detailed view of the modified configuration of
the second preferred embodiment of the present invention.
FIG. 9A is a front view of a fitting pin showing a second modified
configuration of the second preferred embodiment of the present
invention.
FIG. 9B is a side view of the second modified configuration of the
second preferred embodiment of the present invention.
FIG. 9C is a partly detailed view of the second modified
configuration of the second preferred embodiment of the present
invention.
FIG. 10 is an exploded perspective view of a third preferred
embodiment of the present invention.
FIG. 11 is a side sectional view of the third preferred embodiment
of the present invention.
FIG. 12 is a plan view of the third preferred embodiment of the
present invention.
FIG. 13 is an exploded view of a fourth preferred embodiment of the
present invention.
FIG. 14 is a side sectional view of the fourth preferred embodiment
of the present invention.
FIG. 15 is a plan view of the fourth preferred embodiment of the
present invention.
FIG. 16A is a front view of a fining pin showing a modified
configuration of the fourth preferred embodiment of the present
invention.
FIG. 16B is a side view of the modified configuration of the fourth
preferred embodiment.
FIG. 17A is a front view of a fitting pin showing a second modified
configuration of the fourth preferred embodiment of the present
invention.
FIG. 17B is a side view of the second modified configuration of the
fourth preferred embodiment of the present invention.
FIG. 18 is an exploded perspective view of a fifth preferred
embodiment of the present invention.
FIG. 19 is a side sectional view of the fifth preferred embodiment
of the present invention.
FIG. 20 is a plan view of the fifth preferred embodiment of the
present invention.
FIG. 21A is a front view of a fitting pin showing a modified
configuration of the fifth preferred embodiment of the present
invention.
FIG. 21B is a side view of the modified configuration of the fifth
preferred embodiment of the present invention.
FIG. 22A is a front view of a fitting pin showing a second modified
configuration of the fifth preferred embodiment of the present
invention.
FIG. 22B is a side view of the second modified configuration of the
fifth preferred embodiment of the present invention.
FIG. 23 is an exploded perspective view of a sixth preferred
embodiment of the present invention.
FIG. 24 is a side sectional view of the sixth preferred embodiment
of the present invention.
FIG. 25 is a plan view of the sixth preferred embodiment of the
present invention.
FIG. 26 is an exploded perspective view of a seventh preferred
embodiment of the present invention.
FIG. 27 is a side sectional view of the seventh preferred
embodiment of the present invention.
FIG. 28 is a plan view of the seventh preferred embodiment of the
present invention.
FIG. 29 is a side view illustrating a seat for vehicles furnished
with any one of the weight measuring equipments of the first
through seventh equipment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
First Preferred Embodiment
The weight measuring device (hereafter referred to as "device") in
the first preferred embodiment of the present invention will be
described with reference to FIG. 1 through FIG. 3. FIG. 1 is an
exploded perspective view of the present preferred embodiment. FIG.
2 is a side sectional view of the present preferred embodiment.
FIG. 3 is a plan view of the present preferred embodiment.
In FIG. 1, strain detection substrate 2 is fixed to base 1, which
is to be fixed to an object (not shown), with screws 5a, 5b, 5c, 5d
screwed into tapped holes 4a, 4b, 4c, 4d through holes 3a, 3b, 3c,
3d. Hole 6 as a point of action at which the load is applied is
provided at a point where a straight line connecting the fixing
holes 3a and 3d crosses a straight line connecting the holes 3b and
3c. Slots 7 for generating a strain of a detectable level, and
strain resistor 8 whose resistance varies depending upon the amount
of strain are formed around the hole 6.
Fitting pin 9 is made of a material that can withstand more load
than the measuring load. At an end of fitting pin 9 is formed
threaded portion 9a, and at a hexagonal head 9c of fitting pin 9 is
formed insert portion 9b. Also, the fitting pin 9 is inserted into
the hole 6 of the strain detection substrate 2 and fixed by nut 10.
And the base 1 is provided with relief hole 1d.
Arm 19 is provided with hole 16, and is rotatably supported by
support pin 22 between rotation support holes 16a and 16b formed in
the side wall of the base 1. Also, slide holes 19c, 19d are
respectively formed in wing portions 19a and 19b extending from one
end of the arm 19. Second arm 21 is made from a plate material
generally U-shaped, which receives the load of the object to be
measured and is vertically movable. Holes 21c, 21d are respectively
formed in bent wing portions 21a, 21b so that link pin 18 passes
therethrough and the second arm 21 can rotate. With the link pin 18
inserted through the slide holes 19c, 19d and holes 21c, 21d, the
second arm 21 is rotatably supported along with the arm 19.
At one end of leaf spring 13 are disposed fixing holes 13a, 13b in
positions corresponding to tapped holes 14a, 14b of the arm 19, and
at another end thereof is disposed U-shaped notch 13c. The notch
13c is inserted to the insert portion 9b of the fitting pin 9.
Also, the leaf spring 13 is designed so as to be provided with
specific spring characteristics according to the measuring
load.
A method of assembling these components will be described in the
following.
First, the fitting pin 9 is fixed to the strain detection substrate
2 by using the nut 10. Next, the strain detection substrate 2 is
fixed to the base 1 by using the screws 5a to 5d. Also, the leaf
spring 13 is fixed to the arm 19 with screws 23a, 23b. Further, the
arm 21 is connected to the arm 19 by using the link pin 18. In this
state, the U-shaped notch 13c of the leaf spring 13 is inserted to
the insert portion 9b of the fitting pin 9, and the arm 19 is
supported by support pin 22 on the base 1. The support pin 22 is
fixed by nut 23.
The operation of the device will be described in the following with
reference to FIG. 2.
When the weight of the object to be measured is applied via the arm
21 of the device assembled as described above, a force acts on the
arm 21 to move it downward about the support pin 22 as a fulcrum.
The force is transferred via the arm 19 to move the leaf spring 13
upward. This works as a force to pull up the fitting pin 9 fixed to
the strain detection substrate 2, generating a strain in the strain
detection substrate 2 according to the pulling force. The
resistance of strain resistor 8 changes according to the strain,
and the change of the resistance is computed in processing circuit
30 to measure the load. To achieve the purpose that a strain is
generated in the strain detection substrate 2 but the strain
detection substrate 2 is hardly deformed, the leaf spring 13
deforms so that the deformation due to the weight of the object to
be measured via the arm 21 is absorbed by the leaf spring 13.
In this case, the ratio of the distance between the fitting pin 9
and the support pin 22 and the distance from the support pin 22 to
the link pin 18 is freely variable, and therefore, it is possible
to greatly reduce the load applied to the strain detection
substrate 2 in order to enhance the detecting resolution.
Particularly, by increasing the ratio of the distance between the
fitting pin 9 and the support pin 22 and the distance from the
support pin 22 to the link pin 18 two times or more, it is possible
to further reduce the load applied to the strain detection
substrate 2 and to more improve the load detecting resolution.
Also, since the equipment of the present preferred embodiment is
unitized, it is easy to build the device into various types of
equipment. Further, the number of assembling steps can be reduced,
and it is unnecessary to adjust sensor characteristics at the time
of assembly.
The above configuration involves no problem in the case of normal
weight measurement, but when a load exceeding the maximum measuring
load is applied to the device via the arm 21, the load is also
applied to the leaf spring 13 and strain detection substrate 2. As
a result, there is a possibility of permanent deformation or damage
of the leaf spring 13, or breakdown of the strain detection
substrate 2. As a countermeasure, a possible method is to increase
the withstanding characteristics of the leaf spring 13 and strain
detection substrate 2. However, increasing the withstanding
characteristics of leaf spring 13 causes the equipment to increase
in size, and increasing the withstanding characteristics of strain
detection substrate 2 decreases the amount of strain with respect
to the load in the measuring range, resulting in lowering of the
measuring resolution.
In order to address the above problems, as shown in FIG. 1, the
wing portions 21a, 21b of the arm 21 are partly provided with
projections 21e, 21f facing toward the base 1, and when the second
arm 21 rotates about the support pin 22 to move down, reaching a
specific stroke, then the arm comes into contact with the bottom
plate 1c of the base 1. In this case, the stroke is generally
designed to be 2 mm in connection with the maximum measuring load.
On the other hand, when a load in a tensile direction is measured,
projections 19e and 19f disposed at ends of the arm 19 and facing
toward the base 1 come into contact with the bottom plate 1c of the
base 1. The stroke is similarly designed to be 2 mm.
In the above configuration, when the load exceeds the maximum
measuring load, a stopper is formed between the projections 21e,
21f disposed on the arm 21 or the projections 19e, 19f disposed on
the arm 19 and the bottom plate 1c of the base 1. Accordingly, even
when a load or impact load exceeding the maximum measuring load is
applied, the stopper structure receives the load, and thereby,
makes it possible to prevent the breakdown of strain detection
substrate 2 and leaf spring 13.
Further, the dimensions in the widthwise direction (right-and-left
direction in FIG. 1) and lengthwise direction (back-and-forth
direction in FIG. 1) of the notch 13c formed in the end of leaf
spring 13 are set larger than the diameter of the insert portion 9b
of the fitting pin 9. The purpose is to prevent a force from being
directly applied to the insert portion 9b of the fitting pin 9 when
an abnormal force is applied to the object to be measured or to the
device, in the back-and-forth direction, or in right-and-left
direction, during the measurement or in standby mode of the device.
For example, when such abnormal load is supposed to be an impact
load caused due to a collision of vehicles, the load then applied
is 2,000 kg or more. Even in that case, the device of the present
preferred embodiment will not break down due to the durability of
the support pin 22 and the base 1, and in the course of impact
application, the impact is absorbed as the support pin 22 and each
structure deform a little. The size of the notch 13c of leaf spring
13 is determined so as to provide a clearance according to such
deformation. Thus, it is possible to prevent the breakdown of the
strain detection substrate 2 even when impacts are applied to the
device from the back-and-forth direction and the right-and-left
direction.
Second Preferred Embodiment
The weight measuring device (hereafter referred to as device) in
the second preferred embodiment of the present invention will be
described with reference to FIG. 4 to FIG. 9c.
In FIG. 4, U-shaped base 1 is fixed by bolt 51 to an object such as
a chassis 50. Side plates 1a, 1b are provided with rotation support
holes 16a, 16b for the support pin 22, and guide holes 17a, 17b for
the link pin 18. Bottom plate 1c is provided with tapped holes 4a,
4b, 4c, 4d for fixing the strain detection substrate 2, and the
relief hole 1d for threaded portion 9a of the fitting pin 9 and the
nut 10.
The structure, arrangement, and function of the strain detection
substrate 2, the fitting pin 9, and the leaf spring 13 are the same
as those in the first preferred embodiment.
The arm 19 is provided with the hole 16, and is rotatably supported
by the support pin 22 between the rotation support holes 16a, 16b
formed in the side plates 1a, 1b of the base 1, which does not slip
off due to threaded portion 22a formed at the end of the support
pin 22, and the nut 23. Also, the wing portions 19a, 19b extending
from one end of the arm 19 are respectively provided with slide
holes 19c, 19d for guiding the link pin 18 so that the pin moves in
the horizontal direction. Further, the projections 19e, 19f facing
toward the bottom plate 1c of the base 1 are disposed at the end of
the arm 19.
The second arm 21 receives the load of the object to be measured
and is vertically movable and is formed of U-shaped plate material.
The link pin 18 goes through the holes 21c, 21d formed in the bent
wing portions 21a, 21b of arm 21, the slide holes 19c, 19d of arm
19, and the guide holes 17a, 17b, or slots for guiding the pin
vertically, disposed in the side plates 1a, 1b of the base 1. The
link pin 18 is provided with an E-ring, which is not shown, to
prevent the link pin 18 from slipping off. Also, the wing portions
21a, 21b are partly provided with the projections 21e, 21f facing
toward the bottom 1c of the base 1.
A method of assembling these components is described in the
following.
First, the fitting pin 9 is fixed to the strain detection substrate
2 by using the nut 10. Next, the strain detection substrate 2 is
fixed to the base 1 with screws 5a, 5b, 5c, 5d. Also, the leaf
spring 13 is fixed to the arm 19 with screws 23a, 23b. The U-shaped
notch 13c of the leaf spring 13 is inserted into the insert portion
9b of the fitting pin 9, and the arm 19 is supported by the support
pin 22 on the base 1. The support pin 22 is fixed by nut 23.
Further, the slide holes 19c, 19d of the arm 19, the holes 21c, 21d
of the arm 21, and the guide holes 17a, 17b of the base 1 are
aligned with each other, through which the link pin 18 is inserted
and attached to the arm 19, and an E-ring or the like is attached
to prevent the pin from slipping off.
Next, the operation of the device is described with reference to
FIG. 5 and FIG. 6. FIG. 5 is a sectional view of the device
completed as described above and mounted on a seat truck 45 of a
vehicle seat and a chassis 50, and FIG. 6 is a plan view of the
device.
In FIG. 5, when the weight of the object to be measured is applied
to the arm 21, a force acts on the arm 21 to move it downward about
the support pin 22. The force is transferred via the arm 19 to move
the leaf spring 13 upward. This works as a force to pull up the
fitting pin 9 fixed to the strain detection substrate 2, generating
a strain in the strain detection substrate 2 according to the
force. The resistance of the strain resistor 8 changes with the
strain, and the change of the resistance is computed in the
processing circuit 30 to measure the load. To achieve the purpose
that the strain occurs in the strain detection substrate 2, it is
but hardly deformed, the leaf spring 13 deforms so that the
deformation due to the weight of the object to be measured via the
arm 21 is absorbed by the leaf spring 13.
Particularly, at the link mechanism portion where the arm 21 and
the arm 19 are rotatably connected by the link 18, a locus
deviation of the linear motion in the vertical direction of arm 21
from the circular motion of the arm 19 about the link pin 18 is
mechanically buffered. This mechanism is described in the following
with reference to FIG. 7.
For example, when the arm 21 is displaced downward by Y with a load
applied thereto, the arm 19 is accordingly rotated by angle A with
turning radius R about the shaft 22. At the time, the locus of the
arm 21 is linear, while the locus of the arm 19 is circular, and
therefore, locus deviation X is generated as shown in FIG. 7. Here,
an angle A due to the displacement Y and the resultant deviation X
are determined by the following equations 1 and 2.
Lengthwise dimensions of the slide holes 19c, 19d are determined in
anticipation of the deviation X. Also, lengthwise dimensions of the
guide holes 17a, 17b are determined taking into account the stroke
of arm 21. In this way, it is possible to reduce a detection error
superposed on the load. The error occurs when a frictional force is
generated on the slideway by an elastic repulsion due to the locus
deviation, and the frictional force is superposed on the load. And
it is also possible to reduce a hysteresis on a characteristic
curve. In this way, highly accurate device is obtained.
Also, as shown in FIG. 8A and FIG. 8B, as a front view and a side
view of the fitting pin 9, the fitting pin 9 may have an arcuate
inner wall at the insert portion 9b. Thus, as shown in FIG. 8C, the
load acting portion is linearly concentrated, reducing the
variation in acting position of the load transferred to the fitting
pin 9, thereby improving the detection accuracy.
Also, as shown in FIG. 9A and FIG. 9B as the front view of and the
side view of the fitting pin 9, the fitting pin 9 may have a
semicircular inner wall at the insert portion 9b. Thus, as shown in
FIG. 9C, the load acting portion is linearly concentrated, reducing
the variation in acting position of the load transferred to the
fitting pin 9, thereby improving the detection accuracy. The
resultant effect is the same as the fitting pin 9 shown in FIGS.
8A-8C, but the detection accuracy is further improved because of
suppressing the transfer of unnecessary load generated due to a
distortion of the leaf spring 13.
Also, the wing portions 21a, 21b of the arm 21 are partly provided
with the projections 21e, 21f facing toward the bottom plate 1c of
the base 1 to prevent the leaf spring 13 and the strain detection
substrate 2 from a permanent deformation or a breakdown when a load
exceeding the maximum measuring load is applied to the arm 21. When
the arm 19 rotates downward about the support pin 22, reaching the
specific stroke, the projections 21e, 21f come into contact with
the bottom plate 1c of the base 1. On the other hand, in a case of
measuring a tensile load, projections 19e, 19f facing toward the
bottom plate 1c of the base 1, disposed at the end portions of the
arm 19, similarly come into contact with the bottom plate 1c of the
base 1.
Third Preferred Embodiment
A weight measuring device in the third preferred embodiment of the
present invention will be described with reference to FIG. 10
through FIG. 12. FIG. 10 is an exploded perspective view of the
device. FIG. 11 is a side sectional view of the device. FIG. 12 is
a plan view of the device. In the description, phases such as
"up-and-down", "back-and-forth" and "right-and-left", correspond to
the directions of the arrows shown in FIG. 10.
In the present preferred embodiment, the structure, position, and
function of base 1 fixed to an object (not shown), strain detection
substrate 2, and fitting pin 9 are the same as those in the first
preferred embodiment.
The device of the present preferred embodiment includes a fixing
pin 11 as a support portion of a leaf spring 33. The fixing pin 11
is made of a material that can withstand a load higher than the
measuring load, the same as the fitting pin 9. The fixing pin 11 is
provided with a threaded portion 11a at an end portion, and an
insert portion 11b at a hexagonal head portion, which is fixed in a
tapped hole 12 of the base 1. Also, it is so configured that the
insert portion 9b of fitting pin 9 and the insert portion 11b of
fixing pin 11 are substantially the same in height when the base 1
is attached with the strain detection substrate 2 including the
fitting pin 9, and the fixing pin 11.
As shown in FIG. 10, a guide hole 33a for a shaft 34 is formed
nearly in the middle of the leaf spring 33. As a method of making
the guide hole 33a, it is preferable to employ a method of
deformation processing of the leaf spring 33 as shown in FIG. 10 or
a method of combination with other member (not shown). Also, a
dimension of the guide hole 33a with the shaft 34 inserted is made
to be substantially free of play in the right-and-left direction,
and the back-and-forth direction. There are provided U-shaped
notches 33b, 33c at both ends of the leaf spring 33.
The notches 33b, 33c are respectively inserted into the insert
portion 9b of the fitting pin 9 and the insert portion 11b of the
fixing pin 11 in such a manner that the pins are vertically
immovable. Also, the leaf spring 33 is designed to have spring
characteristics in accordance with the measuring load.
Arm 35 as a movable member which receives the load of the object to
be measured and is vertically movable is formed of U-shaped plate.
Bent wing portions 35a, 35b are respectively provided with holes
35c, 35d so that the arm 35 is able to rotate on the shaft 34.
A method of assembling these components will be described in the
following.
First, the fitting pin 9 is fixed to the strain detection substrate
2 by the nut 10. Next, the strain detection substrate 2 is fixed to
the base 1 with screws 5a-5d. Further, the notched portion 33b and
the notched portion 33c of leaf spring 33 are respectively inserted
into the insert portion 9b of fitting pin 9 and the insert portion
11b of the fixing pin 11. Under this condition, the fixing pin 11
is fixed in the tapped hole 12 of the base 1. Next, holes 35c, 35d
and the guide hole 33a of the leaf spring 33 are aligned, and the
shaft 34 is inserted therethrough, and then the leaf spring 33 and
the arm 35 are assembled via slots 26a, 26b formed in the side wall
of the base 1, and the shaft 34 is fixed with nut 17.
The operation will be described with reference to FIG. 11.
When the weight of the object to be measured is applied to the arm
35, the leaf spring 13 suspended between the fitting pin 9 fixed to
the strain detection substrate 2 and the fixing pin 11 fixed to the
base 1 receives the load and deforms in a state of being supported
at both ends. At the time, since the load is concentrated nearly in
the middle of the leaf spring 33, half of the weight of the object
to be measured is applied to the action point of the strain
detection substrate 2. A strain is generated in the detection
substrate 2 in accordance with the load applied. Accordingly, a
resistance of the strain resistor 8 changes, and the change of the
resistance is computed in a processing circuit 30 to measure the
load.
Also, in a case of measuring a tensile load, the arm 35 is pulled
upward, and the leaf spring 33 deforms upward, and then a signal of
opposite polarity is delivered from the strain detection substrate
2.
As is obvious in the present preferred embodiment, only half of the
weight of the object to be measured is applied to the strain
detection substrate 2, and thereby, it is possible to improve a
load detecting resolution.
Also, since the device is unitized, even when the device is built
in various types of equipment, it is easy to assemble and possible
to reduce the number of assembling steps, and it is unnecessary to
adjust the sensor characteristics during the assembly.
The above configuration involves no problem in the case of normal
weight measurement, but when a load exceeding the maximum measuring
load is applied to the device via the arm 35, the load is also
applied to the leaf spring 33 and strain detection substrate 2. As
a result, there is a possibility of a permanent deformation or
damage of the leaf spring 33, or breakdown of the strain detection
substrate 2. As a countermeasure, a possible method is to increase
the withstanding strength of the leaf spring 33 and the strain
detection substrate 2. However, increasing the withstanding
strength of the leaf spring 33 causes the equipment to increase in
size, and increasing the withstanding strength of strain detection
substrate 2 decreases the strain with respect to the load in the
measuring range, resulting in lowering of the measuring
resolution.
In order to address this problem, as shown in FIG. 10, slots 26a,
26b are formed in the side walls of the base 1. The slots 26a, 26b
are longer in the up-and-down direction than a diameter of the
shaft 34, the length of which is set so as to allow the shaft 34 to
be movable in the up-and-down direction for an amount of maximum
deformation of the leaf spring 33 at a maximum measuring load
applied. Thus, when the load exceeds the maximum measuring load,
the shaft 34 comes in contact with the inner walls of slots 26a,
26b, and stops. Accordingly, even when a load or impact load higher
than the maximum measuring load is applied, the stopper structure
receives the load, and thereby, it is possible to prevent the
breakdown of the strain detection substrate 2 or the leaf spring
33.
Further, as shown in FIG. 12, the dimensions in the widthwise
direction (right-and-left direction in FIG. 10) and lengthwise
direction (back-and-forth direction in FIG. 10) of the notches 33b,
33c formed in both ends of the leaf spring 33 are set larger than
the diameters of the insert portion 9b of fitting pin 9 and the
insert portion 11b of fixing pin 11. The purpose is to prevent a
force from being directly applied to the insert portion 9b of
fitting pin 9 when an abnormal force is applied in the
back-and-forth and right-and-left directions, during the
measurement or standby mode to the object to be measured, to the
device, and to the mounting object. For example, when such abnormal
load is supposed to be an impact load due to a collision of the
vehicles, the load applied is 2,000 kg or more. Even in such a
case, though, the device is designed not to break down owing to the
withstanding strength of the shaft 34 and the base 1, in the course
of the impact application, the impact is absorbed by little
distortions of the shaft 34 and other structures. The dimensions of
the notches 33b, 33c of the leaf spring 33 is decided so as to
provide a clearance in accordance with such distortions. Thus, it
is possible to prevent the breakdown of the strain detection
substrate 2 even when impacts are applied to the equipment in
back-and-forth and right-and-left directions.
Fourth Preferred Embodiment
The weight measuring device in the fourth preferred embodiment of
the present invention will be described with reference to FIG. 13
through FIG. 17. FIG. 13 is an exploded perspective view showing an
essential portion of the device in the present preferred
embodiment. FIG. 14 is a plan view of the device of the present
preferred embodiment. FIG. 15 is a side sectional view of the
device of the present preferred embodiment. FIGS. 16A and 16B are a
front view and a side sectional view of a fitting pin showing a
modified configuration in the present preferred embodiment. FIGS.
17A and 17B are a front view and a side sectional view of a fitting
pin showing a second modified configuration of the present
preferred embodiment.
In the present preferred embodiment, the base 1 fixed to an object
such as chassis 50 is provided with tapped holes 4a, 4b, 4c, 4d for
fixing the strain substrate 2, and tapped holes 12a, 12b for fixing
leaf spring 43 at positions higher than the tapped holes 4a through
4d. The structure, arrangement, and function of the strain
detection substrate 2 are the same as those in the first preferred
embodiment.
Fitting pin 9 is made of a material capable of withstanding a load
higher than the measuring load, and is provided with a threaded
portion 9a at the lower part, and an insert portion 9b at a head
thereof. Also, the fitting pin 9 is inserted into the hole 6 of
strain detection substrate 2 and fixed by a nut 10.
A leaf spring 43 is made of a material capable of withstanding a
load higher than the measuring load the same as the fitting pin 9,
and a middle beam 43c at a tip end portion thereof is inserted into
the insert portion 9b of the fitting pin 9 and is held therein.
Also, fixing holes 43a, 43b are formed in end beams 43e, 43f at
both sides of the leaf spring 43 which is fixed by screws 28a, 28b
to the tapped holes 12a, 12b of the base 1. The insert portion 9b
of fitting pin 9 and the middle beam 43c of the leaf spring 43 are
substantially the same in height. Also, at another end portion of
the leaf spring 43 is formed fixing hole 43d as a load input
portion to be attached to the object to be measured.
A method of assembling these components will be described in the
following.
First, the fitting pin 9 is fixed to the strain detection substrate
2 by the nut 10. Next, the strain detection substrate 2 is fixed to
the base 1 with screws 5a, 5b, 5c, 5d. Further, the middle beam 43c
of the leaf spring 43 is inserted into the insert portion 9b of the
fitting pin 9, and is the leaf spring 43 fastened to the tapped
holes 12a, 12b of the base 1 by screws 28a, 28b through fixing
holes 43a, 43b.
The operation will be described in the following with reference to
FIG. 15.
When a weight of the object to be measured is applied to the fixing
hole 43d serving as the load input portion of the leaf spring 43 of
the weight measuring device assembled as described above, a force
is transferred to lift up the fitting pin 9 via the middle beam 43c
of the leaf spring 43 fixed to the base 1. Since the fitting pin 9
is fixed to the strain detection substrate 2, a strain is generated
in the strain detection substrate 2 by a force to lift up the
fitting pin 9. Accordingly, a resistance of the strain resistor 8
changes, and the change of the resistance is computed in the
processing circuit 30 to measure the load.
The end portion of the leaf spring 43 is fork-shaped and only the
middle beam 43c is held by the fitting pin 9, and therefore, a load
reduced at a specific ratio against the input load is applied to
the strain detection substrate 2. Also, it is possible to reduce
the load applied to the strain detection substrate 2 at a specific
ratio by changing a length of notched portions or a width of the
middle beam 43c of the fork-shaped portion of the leaf spring 43,
or by properly changing a distance from the fixing holes 43a, 43b
of the end beams 43e, 43f at both side ends of leaf spring 43 to
the fitting pin 9.
In the present preferred embodiment, since the two end portions of
the end beams 43e, 43f at both side ends of the leaf spring 43 are
fastened to the tapped holes 12a, 12b, a load in a direction
perpendicular to the load detecting direction is hard to be
transferred to the fitting pin 9. Accordingly, it is possible to
suppress unnecessary output generated due to the load in the
direction perpendicular to the load detecting direction, and to
improve the load detecting accuracy. Also, even against an impact
given in the direction perpendicular to the load detecting
direction, it is possible to prevent the breakdown of the strain
detection substrate 2.
Further, by forming inner walls in the insert portion 9b of the
fitting pin 9 arcuate in shape as shown in FIGS. 16A and 16B, or
semicircular as shown in FIGS. 17A and 17B, a contacting portion
between the inner wall formed in the insert portion 9b of the
fitting pin 9 and the middle beam 43c of leaf spring 43 becomes a
line or a point. Therefore, it is possible to reduce friction
between the two components and also to suppress transfer of
unnecessary load generated due to twisting or the like. As a
result, the stability of the sensor output against the load may be
further enhanced.
Also, since the device of the present preferred embodiment is
unitized, when the device is attached to a vehicle seat, for
example, it is possible to reduce the number of assembling steps
and it is unnecessary to adjust the sensor characteristics during
assembly.
Fifth Preferred Embodiment
The weight measuring device in the fifth preferred embodiment of
the present invention will be described with reference to FIG. 18
through FIG. 22B. FIG. 18 is an exploded perspective view of the
device in the present preferred embodiment. FIG. 19 is a plan view
of the device. FIG. 20 is a side sectional view. FIGS. 21A and 21B
are a front view and a side view of a fitting pin showing a
modified configuration in the present preferred embodiment. FIGS.
22A and 22B are a front view and a side view of a fitting pin
showing a second modified configuration of the present preferred
embodiment.
In the present preferred embodiment, the same components as in the
fourth preferred embodiment are given the same numerals, and the
detailed descriptions of the same are omitted, and only differences
will be described in detail.
As shown in FIG. 18, in the present preferred embodiment, the
middle beam 43c of the leaf spring 43 in the fourth preferred
embodiment 4 is divided into a U-shape, while the insert portion 9b
of the fitting pin 9 is H-shaped in section. This configuration
makes it easier to hold the middle beam 43c on the fitting pin 9,
and simplifies the shape of the fitting pin 9, thereby improving
the workability.
Also, as in the fourth preferred embodiment, it is preferable to
form the inner walls of the insert portion 9b of fitting pin 9
arcuate in shape as shown in FIGS. 21A and 21B, or semicircular as
shown in FIGS. 22A and 22B. By this configuration, it is possible
to reduce the friction between the two components and to suppress
the transfer of unnecessary load generated due to a twisting or the
like. As a result, the stability of sensor output against the load
may be further enhanced.
Sixth Preferred Embodiment
The weight measuring device in the sixth preferred embodiment of
the present invention will be described with reference to FIG. 23
through FIG. 25. FIG. 23 is an exploded perspective view showing
the sixth preferred embodiment. FIG. 24 is a plan view, and FIG. 25
is a side sectional view of the device.
In the present preferred embodiment, the same components as in the
fourth preferred embodiment are given the same numerals, and the
detailed descriptions of the same are omitted, and only differences
will be described in detail.
In the present preferred embodiment, as shown in FIG. 23, a load
input end side of leaf spring 43 is divided into three portions,
and side holding portions 43g, 43h and middle holding portion 43i
are bent opposite to each other so that the leaf spring 43 can be
held by link pin 38. And, there is provided arm 39 having fixing
hole 39c to be attached to a load applied portion, which is
suspended by the link pin 38 via holes 39a, 39b. Also, in the side
walls of the base 1 are formed slots 27a, 27b for vertically
guiding the link pin 38 and for controlling an amount of distortion
of the leaf spring pin 43.
In the device configured as described above, since the arm 39 to
which a weight of the object to be measured is applied is supported
by the link pin 38, the arm 39 always receive the load in a
parallel state, and can correctly transfer the load to the strain
detection substrate 2 via the leaf spring 43.
Also, regarding a permanent deformation or a breakdown of the leaf
spring 43 and the strain detection substrate 2 with a load
exceeding the maximum measuring load, they are prevented by the
configuration where the link pin 38 comes in contact with the end
portions of slots 27a, 27b formed in the side walls of the base 1
and function as stoppers.
Seventh Preferred Embodiment
A weight measuring device in the seventh preferred embodiment of
the present invention will be described with reference to FIG. 26
through FIG. 28. FIG. 26 is an exploded perspective view showing
the present preferred embodiment. FIG. 27 is a plan view, and FIG.
28 is a side sectional view of the equipment.
In the seventh preferred embodiment the same components as in the
fourth preferred embodiment are given the same numerals, and the
detailed descriptions of the same are omitted, and only differences
will be described in detail.
As shown in FIG. 26, a load input end side of leaf spring 43 is
provided with a semicircular projection 36. An arm 40 is
substantially box-shaped, and at a top thereof is formed a hole 40c
to be attached to a load applied portion. Also, V-shaped ribs 37a,
37b are provided at an end portion of the base 1. The arm 40 holds
the semicircular projection 36 formed on the leaf spring 43 in such
manner as to enclose the semicircular projection 36, and is
disposed in a substantially parallel arrangement to the V-shaped
ribs 37a, 37b provided at the end portion of the base 1.
In the equipment having a configuration as described above, since
the arm 40 to which the weight of the object to be measured is
applied is supported by the semicircular projection 36 formed at
the load input side of the leaf spring 43, and always receive the
load at one point, it is possible to avoid unnecessary output
generated due to a twisting or the like applied to the arm 40.
Also, as a stopper structure against a load or impact load higher
than the maximum measuring load, a clearance is provided between
the bottom inner surface of arm 40 and the ribs 37a, 37b for an
amount of maximum displacement of the leaf spring 43 for the
maximum measuring load against an upper displacement of the arm 40
in the up-and-down direction. Also, a clearance is provided between
a bottom outer surface of arm 40 and the base surface of base 1 for
an amount of maximum displacement of the leaf spring 43 for the
maximum measuring load against the lower displacement of the arm 40
in the up-and-down direction. In this way, even when a load or an
impact load higher than the maximum measuring load is applied in
the up-and-down direction, the stopper structure receives the load,
protecting the strain detection substrate 2 from excessive load,
and prevents the breakdown of the strain detection substrate 2 and
the leaf spring 43.
Eighth Preferred Embodiment
FIG. 29 is a side view for describing a vehicle seat attached with
any one of the devices shown in FIG. 1, FIG. 4, FIG. 10, FIG. 13,
FIG. 18, FIG. 23 and FIG. 26.
A seat truck 45 is disposed beneath a seat (such as a passenger
seat) 46. The load input end side of the device 44 of the present
invention is attached by bolts and nuts (not shown) to the seat
truck 45. On the other hand, the base 1 of the device 44 is
similarly fixed by bolts and nuts (not shown) to chassis 50. The
devices 44 are disposed at front and rear ends of the seat truck 45
so as to correspond to the four bottom corners of the seat 46. In
this condition, the weight of the person actually sitting on the
seat 46 is measured by the devices 44 disposed at four portions and
computed to judge the weight. At the time, a weight of the seat 46
itself is compensated for by previously setting or storing it in a
memory. As described above, since the devices 44 are disposed at
the front and the rear ends of the seat trucks 45 in such manner as
to correspond to the four bottom comers of the seat 46, it is
possible to judge the weight even when the position of the person
sitting on the seat is changed, and also, to estimate the sitting
position by comparing the loads.
In the above description, an example of disposing four weight
measuring devices at the bottom of the seat 46 has been described,
but the number of the weight measuring devices disposed is not
limit to four. It is also preferable to install one or two weight
measuring devices at a side opposite to the front or rear support
portion of the seat which is rotatably supported, and further, to
increase the number of the weight measuring devices disposed in
order to improve measuring accuracy.
Also, similar results can be obtained by installing the weight
measuring device 44 between the seat 46 and the seat truck 45,
although the configuration is not shown. In this case, since the
weight of the seat truck 45 is not superposed on the strain
detection substrate 2, the weight to be corrected is less,
improving the computing or previous setting accuracy, and as a
result, the accuracy of detection can be enhanced.
As described above, it is possible to realize reliable person
weight measuring equipment by disposing an appropriate number of
the weight measuring devices of the present invention under a
vehicle seat.
INDUSTRIAL APPLICABILITY
According to the present invention, it is possible to obtain a
weight measuring device having a reduced in a load applied to the
strain detection substrate and improved detecting resolution. Also,
since the weight measuring device is unitized, it can be easily
built into various types of equipment including seats for
vehicles.
* * * * *